Demolition device



April 8, 1958 R. G. BOURDON 2,829,633

DEMOLITION DEVICE Filed Jan. 22, 1957 v s Sheets-Sheet 1 April 8, 1958 R. G. BOURBON 2,829,633

1 DEMOLITION DEVICE Filed aanl'zz, 1957 s Sheets-Sheet 2 IN VEN TOR.

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DEMOLITION DEVICE Filed Jan. 22, 1957 s Sheets-Sheet 5 95 INVENTOR- a (91 86 8 EZLSSZZQ ourciow,

United States Patent DEMQLITION DEVICE.

Russet! G. Bourdon, Muskegon, Micro, assignor to The Kaydon Engineering Corp., Muskegon, Mich, a corporation of Michigan Application January 22, 1957, Serial No. 635,391

4 Claims. (Cl. 125-33) This invention relates generally to impact mechanisms, and particularly to a mechanically driven hammer designed for demolition operations, such as breaking con crete stone, and like operations requiring rapid percussive blows.

The device of this invention falls in that category of demolition apparatus which is peculiarly distinct over the familiar pneumatic demolition hammer, in that the driving of the impact mechanism thereof is carried out by a motorized mechanical system.

Generally speaking, the device of the present invention, embodies a rotating impact mass or hammer mechanism which is driven by means of an electrically powered motor through a suitable flexible drive means including a drive belt system; the hammer mass having a pivotal portion periodically engageable with a work chisel means interferingly disposed in the path of rotational movement of the hammer mass, so that the chisel is receptive of periodic blows. It is a general feature of the improved mechanism of this invention that the drive mechanism and system, including the hammer body, are suitably isolated from vibration and shock, particularly repercussion, to give durability to a mechanical demolition apparatus of this type. i

The main object of this invention is to providea new and improved mechanical demolition apparatus.

Another object of this invention is to provide a new and improved demolition apparatus in which a rotating impact mass is suitably driven by means of an electric motor to deliver periodic blows to a rectilineally reciprocal tool, the mechanism including suitable shock absorbing means for protecting the drive motor and interconnecting drive means from the damaging effects of vibration and repercussion.

Still another object of my invention is to provide a new and improved electrically driven demolition device embodying new concepts and features of construction for avoiding vibrational effect on the. operating apparatus and mechanism embodied therein.

Still another object of. this invention is to provide a mechanical style of demolition apparatus employing an electric drive capable of imparting rapid and forceful blows to a reciprocal tool bit with a minimum repercussive effect on the drive unit, thus to promote wear-ability and increase operating life of a tool of this type.

A still additional object of my invention is to provide a new and improved mechanical style of demolition apparatus embodying anv improved hammer mechanism which utilizes improved principles of shock absorption, whereby such hammer mechanism may deliver repeated and successive forceful blows to a reciprocally driven cutting tool in an efficient and effective manner without subjecting the means driving such hammer to damaging vibrational forces.

The above and further objects, features, andiadvantages of this invention will be recognized by those familiar with the art from the following detailed description of. a pre- "ice a. ferred form of my invention appearing in the following specification and illustrated in the accompanying drawings.

In the drawings: 1

Figure 1 is a front elevational view, with parts thereof broken away in section, substantially along the longitudinal center line, demonstrating the arrangement of elements employed in the improved demolition apparatus of this invention;

Figure 2 is an enlarged, partial view in cross-section taken substantially at line 2-2 of Figure 1 and looking in the direction of the arrows to illustrate the flexible drivesystem employed in my new device;

Figure 3 is a cross-sectional view taken substantially along the longitudinal center line of the hammer mechanism seen in Figure l, substantially at line 3-3 of that figure, with parts therein being shown in full elevation;

Figure 4 is an enlarged end-elevational view of the improved hammer mechanism employed in the apparatus of Figure 1, showing the same in a first operating condition;

Figure 5 is an end-elevational view, similar to Figure 4, showing my improved hammer device in a second operting condition;

Figure 6 is a rear-elevational view of the hammer mechanism shown in Figure 4 taken substantially from vantage line 6-6 of Figure 4 and looking in the direction of the arrows thereon;

Figure 7 is a front'elevational view of the same taken substantially at vantage line 77 of Figure 4;

Figure 8 is a cross-sectional view taken substantially at line 88 of Figure 7; and

Figure 9 is another cross-sectional view taken substantially at line 9-9 of Figure 7.

Referring now to the drawings, it will be recognized from Figures 1, 2 and 3, in particular, that the demolition device therein illustrated comprises generally two sections or units, an upper drive unit 11, and a lower impact unit 12, similar to the arrangement employed in the hammer of my prior copending application, Serial No. 429,344, filed May 12, 1954, now Patent No. 2,778,355, dated January 22, 1957, over which the device of the present application constitutes an improved advancement.

The upper or drive section 11, as best seen in Figures 1 and 3, comprises an upper housing section 15 formed with a cylindrical motor chamber 16 in which an-eleo trical drive motor 17 is located; the upper end of the housing outwardly of the motor 17 being enclosed by a cap member 18 held in place by plural screw members 19, or the like. The walls 20 of the housing 15 surrounding the motor chamber 16 are suitably formed with air cooling fins 2tl2ll', while handle members 21 are mounted on opposite sides of the housing section 15, such handles being socketed in resilient cushion means 22 carried by suitable hollow boss projections 2323 formed integrally with the walls 20 of the housing section 15. Disposed adjacent one of the boss portions 23 is a plungertype operating switch 25 which is protected in a suitable chamber projection 26 through which a supply cable 27 passes for supplying electrical energy to the motor means 17.

The motor means 17 includes a substantially vertical armature shaft 30 which is carried between upper and lower bearings 31 and 32, the latter bearing means being located at the lower end of the motor and carried by a lower cap member 33. A suitable cooling fan 34 is mounted on shaft 30 immediately adjacent the lower cap member 33, such fan being rotatably driven with the armature shaft 30 and supplied with air via inlet openings 35 between the housing portion 15 and a lower housing section 40.

Housing section is defined by two chambers 41 and an underdisposed partial chamber 42. Chamber 41 is receptive of the extended armature shaft 30 and a coaxially mounted worm 43, the shaft and worm means being supported by end thrust bearing means 44 located in a web wall 45 disposed between the housing chambers 41 and 42. The worm portion 43 engages a worm gear 46 carried on shaft 47 which extends transversely across housing section 40 and chamber 41, the same being carried adjacent its ends by bearing means 48 mounted in side walls 49-49 of the housing section 48.

The front wall 50 of the housing portion 40 is pro vided with suitable air cooling fins 51 for cooling chamber 41. Wall 59 further includes enlarged boss portions 52-52 which are receptive of bolt members 53 for faster-n ing the upper drive unit 11 to the impact unit 12, as will be described presently.

Located outwardly of the housing wall portions 49 and on shaft 47 are a pair of sheave wheels 55-55, one at each end of shaft 47; the same wheels being held on shaft 47 by key means (not illustrated), and nut members 56, or other suitable locking devices. An external cap or cover housing 57 is arranged to encase or cover over each sheave wheel 55, along with a related secondary and a larger sheave Wheel 60 disposed therebeneath and cooperating with a V-belt 61 trained over each set of associated sheave wheels 55 and 68. For a better understanding of the V-belt drive arrangement, and the association of the housing caps 57 therewith, see Figure 2 of the drawings.

It will be recalled that the housing section 40 includes the upper worm and worm gear chamber 41 and a lower partial chamber 42 which communicates and matingly cooperates with a secondary chamber 42a located at the upper end of housing section 65 associated with the lower impact section 12 of the demolition device.

Housing 65 is arranged to interfit with housing section 40 of the drive unit and includes foreshortened walls 66 and 67 which interfit and mate with corresponding and respectively associated wall portions 66a and 67a of the housing section 40. Side wall portions 68-68 are also included to mate with the wall portions 49 (see Figure 1). The several wall portions 66, 67, and 68 merge in an elongated neck portion 69 lying substantially symmetrical of the longitudinal center line of the demolition device, and forwardly of the axis of rotation for a hammer unit 70 contained in chambers 42-4211.

Hammer unit 70 comprises a substantially cylindrical mass formed by a hammer portion 71 and an interfitted striker portion 72, both of which portions are carried by stub shafts 73 formed integrally with and projecting from opposite sides of hammer portion 71. Suitable cushion bearing assemblies 74 are provided between the wall portions 68 and 49 of the two housing sections 65 and 40 to support the stub shafts 73-73 for rotation. The large sheave wheels 60 are mounted at the outer ends of the shaft portions 73, outwardly of wall portions 49 and 68, the same being enclosed by covers 57, as best viewed in Figures 1 and 2.

The hammer body portion 71 is a substantially T- shaped member of forged or cast metal, the somewhat semi-circular cross-sectional configuration of which may best be viewed in Figure 9. The body portion 71 is further formed with a pair of peripheral ridge portions 75-75 which border a recessed surface 76 at its outer periphery. Side walls or end faces 77-77 of the hammer body are suitably cut away, as at 78 (Figure 8), to form clearance for the reception of arm portions 79-79 of the striker portion 72. The two arm portions 79-79 of the striker portions are spaced apart and joined to the hammer body 71 by means of a pin 80 which passes -through the hammer body 71 and arm portions 79 in a position of displaced parallelism with the longitudinal axis of the stub axle portions 73-73, as best seen in Figure 9 of the drawings.

As in the formation of the hammer body portion 71, the striker member 72 is formed with raised peripheral ridge portions or surfaces 81-81 which extend radially outwardly of an impact section 82. It will further be noted also that the raised surfaces 81 continue along the full length of the arm portions 79, so that such arm portions extend radially beyond the outer surface 84 of the impact section 82.

The hammer body 71 is suitably formed and cut away inwardly of its periphery to provide two surfaces 85 and 86 which lie in substantially transverse interfering relationship with the impact section 82. Particularly, these surfaces are'opposed to corresponding end surfaces 87 and 88 on the striker impact section 82. As best seen in Figure 9, a compression spring 90 is fitted between the hammer body 71 and the striker member 72, the same having one end "thereof socketed in a chamber 91 formed 9 inwardly of surface 85 on the hammer body, While the opposite end thereof fits into socket 92 formed inwardly of surface 87 on the striker impact section 82. Such spring serves normally to separate the hammer body surface 85 and the striker surface 87, so that surface 88 on the striker body portion 82 will engage a centrally disposed shock-absorbing fly-out buffer means 93 carried in a suitable socket formed inwardly of surface 86 of the hammer body. Such shock absorber 93, as with spring 94) may lie symmetrically of a plane passing through the longitudinal or vertical axis of the hammer, as viewed in Figure 7 of the drawings, or such may be located off center if more than one spring or shock-absorbing means is employed in place of spring 90 and absorber 93.

A pair of shock absorbing pick-up buffer assemblies 94-94 are mounted in the outer end of the striker impact section 82 in flanking relation to spring 90. Butlers 94-94 extend beyond surface 87 to engage the opposed surface 85 of the hammer body 71, although the installation of these buffers in the hammer body instead of in the striker portion, as shown, is fully contemplated. In such an installation the buffers would contact surface 85 of the striker.

The impact section 82, in addition to end surfaces 87 and 88, also includes an impact surface 95 for engaging end surface 96 of a sleeve 97 which encases the upper end of a chisel or like impact tool bit 98 which is housed coaxially within the neck portion 69 of housing 65.

Impact tool or chisel 98 is retained in the housing portion 69 by means of a spring loaded pivotal retainer lock 100 adapted to interferingly engage an enlarged collar portion 101 formed on the shank of the chisel 98. The sleeve or cap 97 is suitably sealed with internal walls of the neck portion 69 by seal ring means 102, so as to prevent the escape of lubricants from the interior of the hammer chamber 42-42a.

The chisel 98 is further arranged to be held out of contact and away from collar or sleeve 97 by a latch means 103 operable by suitable linkage means associating with the operating handle members 21, according to the principles and features of a corresponding mechanism disclosed in my copending application 429,344 (Patent No. 2,778,355) of reference herein.

In operation, the chisel or tool 98 receives repeated impact blows at its upper end from the rotating hammer unit 70, which is driven through the V-belt drive means and sheave wheel members 55, 60, and 61, shown in Figure 2. As the hammer unit 70 rotates about the axis defined by the stub axle portions 73, the striker member 72 is held in its outward position, as shown in Figures 3 and 4, during the major part of its rotational cycle with the hammer body. When the impact surface 95 thereon engages the abutment surface 96 of the sleeve member 97 the force of the blow is transferred to the chisel and the striker 72 remains relatively stationary until the rotating hammer mass overtakes and collides with it, bringing together surfaces 85 and 87. Spring 90 is compressed by this relative movement of said members 71 and 72 geese-as and the shock of the collision is greately absorbed by buffer 94. During such relative movement between the hammer body and the impact member, surface 95 slides laterally across the upper face of surface 96 until it is free and clear of the sleeve 97, thereby permitting the striker to be realigned preparatory to the delivery of another blow to sleeve 97. Surface 95 of the striker member clears the upper end of the sleeve 97 by reason of the cut-away surface or portion 105 on the latter. When the hammer body overtages the striker, bufiers 94--94 are compressed at engagement of surfaces 85 and 87. The impact member 72 thereafter rebounds in an opposite direction to rapidly approach the shock absorbing means 93 disposed centrally of the hammer body 71. As the surface 88 engages the shock absorber 93, the released compressive force of spring 90 and shock absorbing means 94--94, plus centrifugal force of the moving striker member 72 is effectively absorbed by the activity of the shock absorber 93; such force being transmitted to the hammer body in the direction of its rotation. This transition in activity of the impact member 72 and the alternate and successive compression of shock absorber means 94 and 93 is illustrated in Figures 4 and 5; Figure 4 showing the impact member 72 at the point of delivering a blow to the chisel sleeve 97, and Figure 5 showing such impact member at its point of engaging the shock absorbing means 94. After an impact blow has been delivered, buffers 9494 contact surface 85, as seen in Figure 5.

In this manner, then, the apparatus of the present invention provides improved advancement in means for absorbing the repercussive and vibrational effects set up by rapid delivery of impact blows to a chisel or tool from a rotating hammer mass and the rebound of such hammer after delivery of a blow. I have found that an arrangement of this character, wherein the repercussive force after delivering the blow to the impact chisel is transferred between the hammer member 71 and the impact striker 72 by shock absorber means, produces improved operating life and efiiciency in a mechanical hammer of this class. It is particularly gratifying to discover that by so absorbing the impact and repercussive effects on the hammer body, little or no vibrational effect is transmitted to the V-belt drive means and motor means. What little vibration is transmitted through the hammer mass to the sheave wheel members 6il60 is adequately absorbed by the flexible V-belt drive means, so that the electric motor 17 and associated worm and worm gear drive are suitably isolated from the shock of vibration and impact.

From the foregoing it is believed that those familiar with the art will appreciate and recognize the improved advancement which my present invention makes in the art. It is particularly important to recognize that while I have herein shown and illustrated the improved demolition device of my invention, particularly the hammer mechanism therein, as embodying certain arrangements of springs and shock absorbing members, greater or fewer shock absorbing members and springs may be employed according to the particular needs and requirements encountered. Therefore, it is to be understood that while I have described my invention in association with a preferred embodiment of its features and concepts, nevertheless, numerous changes, modifications and substitutions of equivalents may be made therein without necessarily departing from the spirit and scope of its inventive aspects. As a consequence, it is not my intention to be limited to the particular form of demolition device herein described and shown, except as may appear in the following appended claims.

I claim:

1. A device for delivering successive impact blows to a reciprocating tool, comprising, a housing, electrical motor means with said housing, a hammer unit mounted rotatably within said housing, drive means including flexible belt means for rotating said hammer unit in response to energization of said motor means, said hammer unit comprising interfitted hammer body and impact striker portions, means pivotally supporting said striker portions on said body portion with the latter having spaced faces opposed by corresponding faces on said striker portion between which the latter is arcuately movable, first buffer and spring means interposed between first opposed faces of said body and striker portions, second buffer means interposed between second opposer faces of said striker and body portions, said first buffer means being compressed by engagement of said body portion with said striker portion after delivery of an impact blow to a tool disposed adjacent said striker portion, said second buffer means being compressed by rebound engagement of said striker portion with said body portion, with the energy absorbed by said second buffer means being transferred to said body portion in the direction of its rotation.

2. A demolition device for delivering percussive blows to an impact tool, comprising, a housing, motor means within said housing, worm and worm gear means driven by said motor means, first sheave wheel means driven by said worm and worm gear means, second sheave wheel means, flexible belt means interjoining said first and second sheave wheel means, a substantially cylindrical hammer unit mounted coaxially with said second sheave Wheel means and rotatable therewith, said hammer unit comprising a body portion rotatably driven with said second sheave wheel means and a striker portion pivotally mounted on said body portion, said striker portion having first and second end faces opposing corresponding third and fourth faces on said body portion, said faces extending inwardly of the peripheral limits of said hammer unit, an impact portion at the outer periphery of said striker portion for engaging an adjacently disposed impact tool, spring means between said first and third faces for urging said striker portion radially outwardly of said body portion to position said impact face thereon for centrifugal engagement with said impact tool, first buffer means between said first and third faces compressible after delivery of an impact blow to said impact tool, second buffer means between said second and fourth faces for compression by the rebound of said striker portion at the release of said first buffer means after the delivery of an impact blow, the energy absorbed by said second buffer means being applied to said body portion in the direction of its rotation.

3. The combination as set forth in claim. 2 in which said first buffer means is carried by said striker portion and said second buffer means is carried by said body portion such that compressive energy is absorbed by each of said buffer means sufiiciently to maintain forces within safe stress limits.

4. In a demolition hammer for delivering repeated percussive blows to an impact tool, the combination comprising, a housing, a hammer unit rotatable about a substantially horizontal axis within said housing, an electric motor within said housing, a mechanical drive means between said motor and .said hammer unit including flexible belt means for rotating said hammer unit, a sleeve member receptive of the shank end of an impact tool mounted adjacent said hammer unit, said hammer unit comprising a body portion rotatably driven by said motor means and a striker portion pivotally carried by said body portion, said striker portion having first and second end faces opposing corresponding third and fourth faces on said body portion, all of said faces extending inwardly of the periphery of said hammer unit, an impact surface formed at the outer periphery of said striker portion for engaging said sleeve member radially beyond said body portion, first shock absorbing means interposed between said first and third faces, second shock-absorbing means interposed between said second and fourth faces, the delivery of an impact blow to said sleeve means requiring contact between said impact face and sleeve member followed by compressive loading of said first 7 shock-absorbing means and impact of said third and first faces, disengagement between said impact face and sleeve member occuring after the delivery of an impact blow to the latter and with sliding motion laterally of the longitudinal axis of said sleeve member, compressive loading of said second shock-absorbing means occurring after release of the compressive load on said first shock- 8 absorbing means at rebound movement of said striker portion toward said body portion in the direction of its rotation, the energy absorbed by said second shock-absorbing means being transferred to said body portion to 5 assist the same in its rotation.

No references cited. 

